Last few years have seen a dramatic rise in the number of applications of reactive distillation (RD). This useful technology is now being applied for any scale of operation-from manufacture of fine chemicals to that of bulk chemicals. This article reviews the very recent applications and serves as a supplement for the exhaustive review on this subject by Sharma and Mahajani (2003). It not only furnishes the information on the ongoing research in the existing applications but also elaborates the newly discovered applications such as manufacture of phenol, linear alkyl benzene, carbonates, chlorosilane derivatives and chiral chemicals. Multiple reactions in RD, failure of RD in some cases and new RD configurations to increase the overall yields are some of the additional aspects being covered.

The esterification reaction of acetic acid with n-butanol in a continuous catalytic distillation system has been studied. The products of esterification reactionsviz, water and butyl acetates are separated by distillation during the course of the reaction, to overcome the equilibrium limitations. A 3-m-tall column with reactive and nonreactive zones, packed with a commercial catalytic packing (KATAPAK-S) and noncatalytic wire gauze packing, was used for this purpose. For a feed concentration corresponding to that obtained in a one-stage continuously stirred tank reactor at reaction equilibrium, conversion of ∼100% was realized, with selectivity on the order of 99%. Interestingly, in most of the experiments, the bottom stream contained butyl acetate that was almost free of acetic acid. The influence of various operating parameters, such as feed flow rate, feed composition, feed location, and boil-up rate, on the conversion, selectivity, and separation was studied. A dynamic equilibrium stage model was developed and solved to predict the transient and steady-state results. Reasonably good agreement between the experimental and simulation results was realized.

A new approach to reactor model building for two-phase absorption processes is developed by considering simultaneously mass and heat transfer phenomena, and chemical reaction mechanism and kinetics. In particular, the interaction of mass and heat transfer with chemical reaction over the reactor design is considered to improve the accuracy of the simulation results. A novel methodology is applied to identify suitable reaction mechanisms and kinetics based on limited experimental data. This methodology allows the engineer to develop feasible reaction mechanisms in a systematic approach. Importantly, the required scope for any further lab experiments is identified, especially when the modeling needs further clarification for the reaction kinetics or mechanisms. In this way, a more robust reactor design can be achieved by making full use of experimental information, saving unnecessary laboratory and pilot plant experiments. For a case study, chlorine absorption to oleic acid is applied to the modeling of a laminar jet absorber.

This research has focused on a new methodology to develop a rigorous reactor model for gas−liquid chemical reactions in absorption processes. This involves simultaneous chemical reaction and mass transfer between two phases. In particular, all feasible chemical reaction mechanisms and kinetics are considered for the modeling to improve the accuracy of the simulation results. Detailed mathematical modeling is developed to identify physical properties of the key components. For a reactor design, a packed bed reactor has been developed with two different types of modeling approaches. The results of two separate models are compared with the laboratory experimental data. For a case study, CO 2 absorption to monoethanolamine (MEA) solution is used based on a wide range of experimental data from both laminar jet absorber and packed bed column.

No abstract